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Frequently Asked Questions (FAQ)
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AnswerIn RFEM, you can design surfaces and members of reinforced concrete.Members are designed in the add-on module RF-CONCRETE Members or RF-CONCRETE Columns.Surfaces are designed in the RF-CONCRETE Surfaces add-on module (optionally with RF-CONCRETE Deflect or RF-CONCRETE NL).Reinforced concrete solids can not be designed in RFEM. There is currently no add-on module for the reinforced concrete design of solids.However, you can create solids with the material "Concrete" and select For example, you can determine the stresses within the solid. Optionally, you can insert a result beam into the solid that is used to convert the results of the solid into member internal forces.The result beam can subsequently be designed in RF-CONCRETE Members or RF-CONCRETE Columns.
AnswerNo, this is unfortunately not possible.If the option "Tension Stiffening" is not applied for the calculation, the distribution coefficient ζ is either "0" for "uncracked" or "1" for "cracked". See also the technical article linked below for the distribution of the distribution coefficient ζ.But the manual specification of z. Eg ζ = 0.5 is not possible.
AnswerThe concrete tensile strength f ct, eff, wk = f ctm x crack width factor is applied.
AnswerNo, this is unfortunately not possible.
AnswerNo, this is unfortunately not possible.The intermediate values from the calculation (for example, the applied static depth d for the shear force design) are only available for the selected FE node or grid point when you open the "Design Details" dialog box. But not for all FE mesh nodes of the designed surfaces.Therefore, these intermediate values can not be used for a graphical display on the model, but only in tables in the design details.
AnswerIn this case, the method of check and the type of the 2D position are important.When using the analytical method (RF-CONCRETE Deflect), it is possible to perform a calculation in 2D positions. When using the nonlinear method (RF-CONCRETE NL), the calculation for 2D XY (u Z / φ X / φ Y ) is not possible. In the nonlinear calculation, among others Shrinkage is represented internally as an expansion load, which is not possible in this type of 2D position due to the limited degrees of freedom.Convert 2D to 3D PositionIn the general data, it is possible to simply convert a 2D position into a 3D position. For the supports, all degrees of freedom not contained in the 2D position are fixed when converting to a 3D position (see the video).
AnswerThis may be related to the curtailment of the provided reinforcement.If no curtailment is activated, a uniform reinforcement is designed across the entire structure (Figure 01).
The curtailment of the reinforcement can be activated in the "Longitudinal Reinforcement" tab of the add-on module (Figure 02).
After activating the curtailment, it is possible to define a number of zones. The higher the number of zones is, the more precisely the provided reinforcement can follow the distribution of the required reinforcement (Figure 03).
Yes, it is because the CONCRETE module of RSTAB 8 also includes the nonlinear reinforced concrete design. Thus, you can activate the 'Nonlinear Analysis (State II)' in the 'Ultimate Limit State' tab.
In the detail settings for the nonlinear design, you can select the 'General Design Method for Members in Axial Compression acc. to Second Order Theory'.
It is important that you define the imperfections in RSTAB and apply load curves (CO) according to the second-order analysis for the design, no result combinations (RC)!
Note on RFEM 5:
In RFEM 5, the same procedure is possible in RF-CONCRETE Members. However, the add-on module RF-CONCRETE NL in RFEM is required for the non-linear reinforced concrete design.
AnswerIf any circular cross-sections are available in a structure, they can only be designed with peripheral reinforcement (Figure 01). This is due to the fact that there is no "top" and "bottom" for a circular cross-section.Only one reinforcement layout can be defined for each reinforcement group in RF-CONCRETE Members. If the circular cross-section and the rectangular cross-section are designed together, only the peripheral reinforcement can be used for all cross-sections.To avoid this restriction, you have to define another or separate reinforcement group (Figure 02).
AnswerDifferences resulting from the determination of the deformation in the cracked state can have different causes. The following points should be checked for deviations:
Is the same calculation method applied?
RF-CONCRETE Deflect uses an analytical analysis approach according to EN 1992-1-1 7.4.3.RF-CONCRETE NL uses a physically nonlinear analysis approach.More detailed information about the calculation methods can be found, for example, in the RF-CONCRETE Surfaces Guide in Chapter 2.7 and 2.8.
Is the same initial structure available?
The results of the linear calculation provide the best tool for consideration if the underlying system should be taken for equivalent. The linearly determined deformation of the underlying combination should be approximately equal. Any possible differences in the linear deformation may be increased in the cracked state in connection with the deformation analysis.
Are the same effects taken into account?
When performing a comparison, make sure that the same effects as for example creep and shrinkage are taken into account (Figure 02).
Are the same input values available?
Furthermore, it should be checked in connection with the deformation analysis if the same input values are available. In this case, it is necessary to pay particular attention to whether the applied reinforcement (Figure 03) and the lever arm or concrete cover are the same.
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